Ashes of wood-burning ovens. II Industrial residue useful as an amendmer for improving soil fertility

Abstract

The chemical composition of ash from six wood-burning ovens is characterized. It was found that ash from wood waste of native species and from Eucalyptus globulus have higher levels of Ca, K, Mg, and P soluble in 3% hydrochloric acid compared to ashes from Pinus radiata. Given the potential for increased use of P. radiata wastewood as fuel, P. radiata ash was chosen to study the effects upon soil fertility of adding ash to soil. Three soil types from southern Chile were chosen: a volcanic ash soil ("trumao"), a red clay soil, and a brown metamorphic soil. Ash was added in proportions of 0.5%, 1.0%, and 2.0% by dry weight for each. After a period of 41 days, the content of nutrient elements was determined using extracts of destilled water, 0.1 N ammonium chloride, 1% citric acid, or 3% hydrochloric acid. 321 mm of rain fell during this 41-day period. Results verify a 2-fold to 10-fold or more increase of nutritive elements in the soils resulting from ash amendment, compared to levels for extracts from original unamended soils.